Production of benzines, benzenes, and other hydrocarbons from coal tars and oils



R. E, GOLDSBROUGH Filed Feb. 5, 1931 IN V EN TOR.` E Goldsbmu xwnkimk Q k Sept. 19, 1933.

PRODUCTION OF BENZINES, BENZENES, AND'OTHER HYDROCARBONS FROM'COAL TARS AND OILS Patented Sept. 19, 19,33

PRODUCTION oF BENzrNEs,

BENZENES,

AND OTHER HYDROCARBONS FROM COAL TARS AND OILS" Robert Edwin coiasbrough, Slough, England Application February 5, 1931, Serial No. 513,789,

and

in Great Britain October 21, 1930 2 Claims. Cl. 196---520` This invention relates to the conversion of all kinds of coal tars and the like into new and useful products including motor spirit, to be used more particularly as fuel in internal combustion engines, and also kerosene-like products, lubricating oils, pitch and supplies of gases containing unsaturated and saturated hydrocarbons.

The invention consists in a process for the pro- Y duction of hydrocarbons particularly suitable for use as fuel in internal combustion engines, charaoterized in that steam superheated at over 700 C. is mixed with coal tar or the like heated below the cracking point, the mixture being expanded and subjected to` catalytic reaction and to decreasing temperature and pressure with turbulence, the vapours thus obtained being condensed and subjected. to fractional distillation.

According tothe present invention, I superheat steam in non oxidizing conduits such as nickel chromium tubes to a temperature of over 700 degrees centigrade. At these temperaturesk in contact'with the non oxidizing conduits the steam is partly decomposed into nascent oxygen and hydrogen.

The tars or the erably to a temperature just below their cracking point, at which they deposit solid carbon.

The steam and the heated tars or the like are injected at a pressure above two atmospheres, and preferably about four atmospheres, into a mixing chamber composed of non oxidizing material. In the mixing chamber the intimate mixing of the finely divided particles of the tar with the oxygen and hydrogen of the steam is achieved.

The mixing chamber is joined to a retort by means of a Venturi tube which allows the expansion of the mixture into the retort without substantial loss of velocity.

The retort is made up of a series of chambers of different sizes joined by narrow passages and may be similar to that [illustrated in my British Patent specification No. 266,765 but means must be employed to maintain a pressure above the atmospheric pressure inthe retort.

The'retort is composed of or lined with an alloy which sets up catalytic reaction and may be of the following mixture:

Nickel Chromium 30% centages of the ingredients may be appreciably the retort.

' which number from seven like are separately heated, prefrentry for tar, 3 is the ture of 50,0 to 600l degrees centigrade. Thus, a definite temperature gradient is provided throughout y.As detailed above the retort is divided into a number of chambers. The largest of these 10 is at the entry end and is termed the` expansion chamber, and this is joined to the second and smallest chamber 4 by means of a narrow passage 12 which sets up turbulence and local pressure changes. The succeeding chambers i to thirteen for different tars are of gradually increasing size, so that, starting from the second chamber the vapour mixture expands in a series of stages giving a denite pressure gradient throughout the retort, together with local pressure changes set up by the narrow passages.

l is the entry for superheated steam, 2 is the mixing chamber, 9 is a gas burner for heating, 5 is a brickwork, 11 is insulation, 6, 6 are condensers, 8, 8 are outlets from condenser to refinery, .7 is the gas outlet to gas holder.

The whole retort is therefore composed of or lined with catalytic materials and is constructed and heated to give a temperature and a pressure gradient to the vapours passing through it.

In operation, the steam, tar and retort are heated in the manner hereinbefore described.

The partly dissociated steam and the heated tar are injected into the retort in the proportions of about one of steam to six of tar at about 4 atmospheres pressure. Immediate reactions take place between the carbon, hydrogen and Oxygen of the tars and the nascent oxygen and hydrogen of the steam under the action of -the catalyst and of the pressure generated in the rst chamber of the retort. These reactions are carried further by the local pressure changes and the gradually decreasing temperatures and pressures which give the heat conditions for the various chemical combinations.

After passing through the retort the vapours are cooled, and the liquors which condense out are 'similar to crude mineral oil and give low boiling fractions suitable for motor spirit, and higher boiling fractions suitable for kerosene. lubricating oil and pitch.

.These higher boiling fractions may be recirculated to obtain further supplies of motor spirit.

Coal tar oils may be used instead of coal tars, according to the present invention.

It has been found that tars containing tar acids produce low boiling hydrocarbons similar to benzol and toluol which are unstable when exposed to actinic light in the presence of oxygen and change back to acids and gummy and resinous substances. I have found that by mixing a small amount of formaldehyde or the like with the low boiling fractions either before or after distillation this condition is avoided and the hydrocarbons remain stable under the action of actinic light. The usual antigum substances, such as a mixture of the three isomeric cresols may also be used.

After passing through the condenser-s, a rich xed gas passes over which contains quantities of aromatic liquid hydrocarbons which are removed by scrubbing the gas with gas oil or by any other known means. The gas may then be used to heat the retort and superheater or owing to the high percentages of saturated and unsaturated hydrocarbons which it contains it may be used for other purposes.

The following is an example of the process conducted in the foregoing apparatus:

100 English gallons of a primary tar, consisting of a mixture of aliphatic hydrocarbons with a small amount 0f aromatic hydrocarbons and about 40 per cent. of tar acids and other accessory constituents such as bases and the like, are

injected, after having been preheated to about 200 C., into the retort or retorts by Way of a mixing chamber into which superheated steam is simultaneously injected. For 100 gallons of primary tar, 150 lbs. of steam may be used. The temperature of the retort is approximately 850 C. in the lower and middle portions and approximately 600 C. in the upper portion.

'Ihe vapour mixture leaving the retort together with the steam is cooled vin a suitable fractional separating apparatus to a temperature at which the steam andoil vapours of the light fraction separate from the higher oil fraction. 'I'he steam is condensed together with the vapours of the light fraction in a suitable condensing apparatus, whereas the heavy fraction, which, for example may boil above 230 C., remains in the fractional separating apparatus. This latter fraction may be used again and recirculated for the purpose of producing a further quantity of light oil.

By operating in the manner above described, it is possible to obtain from 100 gallons of primary tar, about 40 gallons of a light fraction Y which, after refining, is suitable as a first class motor spirit and about 50,gallons of hea'vy fraction which is either wholly or partly suitable for retreatment; the loss of about 10 per cent. is accounted for by the formation of permanent gas during the process.

'What I claim is:

, 1. In aprocess for the production of benzines, benzenes and other light hydrocarbons from bituminous material such as tars and tar oils, injecting said material together with steam at a pressure above two atmospheres into a series'of reaction zones having surfaces of nickel-chromiuni alloy containing small proportions of silicon, zinc and iron, expanding the mixture into the first zone while maintaining the pressure above atmospheric pressure, vaporizing the bituminous material in said rst zone at a temperature of from 700 to l000 C., passing the vapor mixture through the succeeding zones of alternately restrictedand enlarged cross section to promote turbulence and pressure changes, and attaining 500 to 600 C. at the end zone.

2. In a process for the production of benzines, benzenes and other light hydrocarbons from bituminous material such as tars and oils, the steps of injecting said material together with steam at a pressure not exceeding about 4 atmospheres into a reaction zone having surfaces made of an alloy containing about nickel and chromium and the remainder containing small amounts of silicon, zinc and iron, vaporizing the bituminous material in said zone of varying cross sections at a temperature suicient to partly decompose the steam, and reacting the mixture of vapor and gases at gradually reduced temperatures.

ROBERT EDWIN GOLDSBROUGH. 

